An "extremely dangerous" man armed with a gun is wanted over the death of a Perth mum.

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Police hunt second man in relation to Perth mothers death

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VIDEO Police hunt second man in relation to Perth mothers death Police hunt second man in relation to Perth mothers death

Rebecca Jane Gascoigne, 35, was found dead in a Mitsubishi Lancer on the Mitchell Freeway near the Cedric Street off-ramp about 12.35am on Saturday.

WA Police on Sunday released images of the Scarborough mum-of-three and of Shawn Adam Newton, who they want to speak to over Ms Gascoigne's death.

"He is considered extremely dangerous, the public are warned not to approach him as he is in possession of a firearm," the Homicide Squad's Detective Senior Sergeant Dean Bailey told reporters on Sunday.

Police have released a photos of Shawn Adam Newton Photo: WA Police Media
Rebecca Gascoigne was found dead in a Mitsubishi Lancer on the Mitchell Freeway in Perth. Photo: 7 News

Newton and Ms Gascoigne knew each other, but Det Snr Sgt Bailey would not say how.

Police currently have a 49-year-old man, who was the driver of the Mitsubishi, in custody, helping them with their investigation. No charges have been laid.

Ms Gascoigne's body was found in a car on a Perth freeway. Photo: 7 News
Police investigating at the scene where Ms Gascoigne's body was found. Photo: 7 News

"A gentleman who's assisting police approached officers at another incident on the Cedric Street ramp and identified that the body was in his vehicle," Det Snr Sgt Bailey said.

Newton, 42, of Lockridge, is described as fair skinned, about 186cm tall, with a medium build, shaved dark hair and brown eyes.

Anyone who knows of Newton's whereabouts is asked to call police on 131 444 or Crime Stoppers on 1800 333 000.

AAP

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